Private Bag 6995, Wellington 6141, New Zealand iv Johnstone’s Hill tunnel monitoring 2010 –...

ISBN 978-0-478-40792-1 (online)

NZ Transport Agency

Private Bag 6995, Wellington 6141, New Zealand

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[email protected]

www.nzta.govt.nz

Kuschel, G, L Wickham (2013) Johnstone’s Hill Tunnel air quality monitoring March to July 2010:

Summary report. NZ Transport Agency, 2013. 44pp.

[Gerda Kuschel, Emission Impossible Ltd, Suite 1-6, 72 Dominion Road, Mt Eden, Auckland 1024.

www.emissionimpossible.co.nz]

This publication is copyright © NZ Transport Agency 2013. Material in it may be reproduced for personal

or in-house use without formal permission or charge, provided suitable acknowledgement is made to this

publication and the NZ Transport Agency as the source. Requests and enquiries about the reproduction of

material in this publication for any other purpose should be made to the Research Programme Manager,

Programmes, Funding and Assessment, National Office, NZ Transport Agency, Private Bag 6995,

Wellington 6141.

Keywords: air quality, tunnel monitoring, nitrogen dioxide, particulate matter, state highways

Page i

Johnstone’s Hill tunnel monitoring 2010 – summary report

An important note for the reader

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The objective of the Agency is to undertake its functions in a way that contributes to an affordable,

integrated, safe, responsive and sustainable land transport system. Each year, the NZ Transport Agency

funds innovative and relevant research that contributes to this objective.

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judgement. They should not rely on the contents of the research reports in isolation from other sources of

advice and information. If necessary, they should seek appropriate legal or other expert advice.

Acknowledgements

This report summarises the results of a comprehensive monitoring programme that was undertaken with

the assistance of the following agencies:

• Auckland Motorway Alliance (AMA)

• Institute of Geological and Nuclear Sciences (GNS)

• National Institute of Water and Atmospheric Research (NIWA)

• NZ Transport Agency

• Watercare (WSL)

Page ii


Foreword

The NZ Transport Agency is a Crown entity responsible for managing the New Zealand state highway

system, including six major road tunnels as follows:

• Mt Victoria Tunnel in Wellington (opened in 1931)

• Homer tunnel which provides access to Milford Sound (opened in 1953)

• Lyttelton Tunnel near Christchurch (opened in 1964)

• Terrace Tunnel in Wellington (opened in 1978)

• Johnstone’s Hill Twin Tunnels northwest of Orewa (opened in 2009)

• Victoria Park Tunnel in central Auckland (opened in 2011).

The Transport Agency is reviewing the management of these existing tunnels to assist in the design of

future upgrades and to develop standards and guidelines to cover new tunnels. As part of the review, the

Transport Agency has already completed two projects to provide advice on the management of air quality

both in and around road tunnels, as follows:

1. Guidance for the management of air quality in road tunnels in New Zealand1 and

2. Stocktake of the air quality in and around existing state highway tunnels2.

The first report proposed a set of guidelines for occupational and non-occupational exposure in tunnels.

These have now been adopted as interim guidelines by the Transport Agency3. The second report reviewed

the monitoring of air quality and other key parameters that have previously been undertaken for the

existing tunnels and highlighted the key gaps that need to be addressed to improve future tunnel

management.

Complementary to these two projects, the Transport Agency has embarked on a programme of detailed

monitoring for each of the six tunnels. The programme is designed to fill in the knowledge gaps identified

and develop a robust set of findings, upon which to base future tunnel management plans such as

upgrades of existing tunnels and the design of new tunnels.

Tunnel monitoring campaigns are critical for ensuring that the Transport Agency ‘maintains and operates

all air quality management/air pollution mitigation measures, such as road tunnel ventilation systems,

correctly to ensure they continue to provide the designed level of mitigation’ in order to meet objectives

set in the Environmental Plan4. The first tunnel monitoring campaign was undertaken for the Mt Victoria

and Terrace tunnels in Wellington between September and December 20085.

This report summarises the findings of the second tunnel monitoring campaign, undertaken for the

Johnstone’s Hill Twin Tunnels in March to July 2010.

1 NIWA (2010a). Guidance for the management of air quality in road tunnels in New Zealand, NIWA Report AKL-2010-045 prepared for NZ Transport Agency, December 2010 2 NIWA (2010b). Stocktake of air quality in and around state highway tunnels, NIWA Report AKL-2010-016 for NZ Transport Agency, April 2010 3 NZ Transport Agency (2009). NZTA standards for air quality in road tunnels, Memo to Value Assurance Committee by Carl Reller, Rudolph Kotze, and Rob Hannaby, 24 September 2009 4 Transit NZ (2008). Environmental Plan, version 2, Transit NZ (now NZ Transport Agency), June 2008 5 NIWA (2009). Air quality monitoring in the Terrace and Mt Victoria tunnels, Wellington, NIWA Report AKL-2009-021 prepared for NZ Transport Agency, June 2009

Page iii


Contents

Summary 1

1. Introduction 4

1.1 Background 4

1.2 Objectives 4

1.3 Agencies involved 5

1.4 Report layout 5

2. Methodology 6

2.1 Site description 6

2.1.1 Tunnel purpose and location 6

2.1.2 Geometry and ventilation 7

2.1.3 Traffic flow and fleet composition 8

2.1.4 Traffic monitoring 9

2.1.5 Receiving environment 10

2.1.6 Meteorological conditions 11

2.1.7 Previous monitoring 11

2.2 Parameters measured 12

2.2.1 Permanent monitoring 13

2.2.2 Campaign monitoring 13

2.3 Assessment criteria 19

2.3.1 In-tunnel air quality 19

2.3.2 External air quality 20

2.4 Data processing/analysis 20

2.4.1 Permanent monitoring 20

2.4.2 Gaseous (CO and NO2) monitoring 21

2.4.3 Particulate monitoring 21

3. Results 22

3.1 In-tunnel ventilation 22

3.1.1 Air flow 22

3.1.2 Jet fan operation 23

3.2 In-tunnel traffic 23

3.3 In-tunnel air quality 24

3.3.1 Carbon monoxide 24

Page iv


3.3.2 Nitrogen dioxide 26

3.3.3 Particulate matter 28

3.4 Meteorology 29

3.5 Source apportionment 30

4. Key findings 31

4.1 Diurnal trend 31

4.2 Holiday traffic 32

4.3 Operational monitoring of in-tunnel parameters 33

4.3.1 Tunnel ventilation 33

4.3.2 Sensor performance 33

4.4 In-tunnel dispersion 34

4.5 External air quality 36

4.6 Heavy duty vehicles 36

5. Conclusions and recommendations 39

5.1 Conclusions 39

5.1.1 Compliance with standards and guidelines 39

5.1.2 Disproportionate impact of heavy duty vehicles 39

5.2 Recommendations 40

5.2.1 Key parameters for future management 40

5.2.2 Design suggestions for future tunnel monitoring campaigns 40

6. References 42

7. Glossary 43


Summary

The NZ Transport Agency currently manages six major road tunnels as follows:

• Mt Victoria tunnel in Wellington (opened in 1931)

• Homer tunnel which provides access to Milford Sound (opened in 1953)

• Lyttelton tunnel near Christchurch (opened in 1964)

• Terrace tunnel in Wellington (opened in 1978)

• Johnstone’s Hill twin tunnels northwest of Orewa (opened in 2009)

• Victoria Park Tunnel in central Auckland (opened in 2011).

The Transport Agency has embarked on a programme of detailed monitoring for each of the six tunnels.

Tunnel monitoring campaigns are critical for ensuring that the Transport Agency ‘maintains and operates

all air quality management/air pollution mitigation measures, such as road tunnel ventilation systems,

correctly to ensure they continue to provide the designed level of mitigation’ in order to meet objectives

set in the Environmental Plan6. The first tunnel monitoring campaign was undertaken for the Mt Victoria

and Terrace tunnels in Wellington between September and December 20087.

This report summarises the findings of the second tunnel monitoring campaign, undertaken in the

northbound tunnel of the Johnstone’s Hill Twin Tunnels in 2010. The Johnstone’s Hill Tunnels operate

permanent in-tunnel sensors which measure carbon monoxide, air flow and jet fan operation. In addition

to these, measurements were also taken of:

• in-tunnel carbon monoxide (CO) using a continuous analyser for comparison with the in-tunnel

sensor

• in-tunnel nitrogen dioxide (NO2) using a continuous analyser at one point and an array of passive

samplers (to provide an indication of how concentrations vary along the tunnel length)

• external NO2 using an array of passive samplers (to provide an indication of how concentrations

vary before, inside and after the tunnel)

• in-tunnel particulate8 (PM10

) using a continuous analyser, with a set of individual samples collected

using a streaker sampler for subsequent source apportionment analysis

• external wind speed and wind direction for comparison with in-tunnel air flow and

• traffic data (counts, % heavy commercial vehicles and speed) using dual inductive loops installed in

each lane.

Campaign monitoring was undertaken for three months from late March to early July 2010 to enable a

comparison of weekday and weekend emissions, and to investigate the impact of long holiday weekends

(Easter in April and Queen’s Birthday in June were included in the campaign).

The key findings were:

• In-tunnel air quality in the northbound tunnel is well within the Transport Agency interim standards

for CO and NO2 set to protect workers and the general population travelling through the tunnel.

6 Transit NZ (2008). Environmental Plan, version 2, Transit NZ (now NZ Transport Agency), June 2008 7 NIWA (2009). Air quality monitoring in the Terrace and Mt Victoria tunnels, Wellington, NIWA Report AKL-2009-021 prepared for NZ Transport Agency, June 2009 8 PM

10 is particulate matter less than 10µm in diameter


• The key parameters affecting in-tunnel air quality are traffic volume and composition (specifically

the proportion of heavy duty commercial vehicles). However, it is likely that external wind speed

and in-tunnel ventilation are also important.

• The in-tunnel CO sensors perform well relative to a regulatory method air quality monitor but need

to be calibrated at least once every 12 months to correct for instrument drift - particularly as their

output is used as the trigger for activating the jet fans.

• External air quality near the northern exit of the tunnel appears to be close to the World Health

Organisation’s annual average guideline for NO2 but this was based on three months (only) of

monitoring. It should be noted that the nearest potentially sensitive receptors (ie residences) are

located more than 300m away from either portal; therefore it is unlikely that any person is being

exposed to ‘high’ NO2 levels for a year.

The principal recommendations for future work include:

• All in-tunnel equipment should be connected to a data management system (rather than overwritten

each day) which generates and records averages against the Transport Agency interim standards (ie

15-minute averages). This would enable the tunnel operation to be reviewed periodically to confirm

all Transport Agency standards are being met and/or to investigate possible causes of non-

compliance. It may further be used to signal emerging trends that may impact tunnel performance.

• All in-tunnel sensors should be checked frequently and calibrated at least annually. The northbound

in-tunnel CO sensor is subject to upwards drift and on current trends may trigger the jet fans

(erroneously) by May 2014. It is likely the southbound in-tunnel sensor is also drifting9.

• Campaign monitoring should be undertaken periodically (ideally every five years) to validate the

performance of the in-tunnel sensors and confirm (through the use of regulatory method

equipment) that the Transport Agency in-tunnel standards are being met. This monitoring should

be for key air pollutants (eg CO, NO2 and PM

10), on-site meteorology and on-site traffic. There would

be considerable value in undertaking passive sampling of NO2 inside and outside tunnels on an

extended basis.

• Internationally, tunnel monitoring campaigns are also employed to research other aspects of vehicle

emissions management, which are highly relevant to New Zealand. These include verifying predicted

vehicle emission factors/trends, developing new emission factors for sources such as road dust,

assessing air pollution dispersion from tunnel portals and investigating the toxicity of emissions.

9 Since the tunnel monitoring campaign ended, both in-tunnel CO sensors have been repaired and re-calibrated several times. Both sensors are now being serviced annually with more regular calibration checks being undertaken. T Sullivan (2013) of Auckland Motorway Alliance, pers. comm., 4 February


A well-designed and well-coordinated future campaign could address most (if not all) of this report’s

recommendations and lead to improved design/management of tunnels in the state highway network as

well as furthering a better understanding of general vehicle emissions management in New Zealand.

This report briefly reviews the monitoring that was undertaken and summarises the data that were

collected. More detailed information relating to the specific phases of the tunnel monitoring campaign is

available in the following technical reports:

• Continuous air quality monitoring10

• Passive NO2 monitoring11

• Particulate matter concentration, composition and sources12

10 WSL (2010a). Johnstone’s Hill tunnels – Continuous air quality monitoring report 30 March to 13 July 2010, Report prepared by Watercare Services Ltd for NZ Transport Agency, August 2010 11 WSL (2010b). Johnstone’s Hill tunnels – Passive nitrogen dioxide air quality monitoring report March to June 2010, Report prepared by Watercare Services Ltd for NZ Transport Agency, August 2010 12 GNS (2011). Concentration, composition and sources of particulate matter in the Johnstone’s Hill tunnel, Auckland, GNS Science Report 2010/296 prepared for NZ Transport Agency, November 2011


1. Introduction

1.1 Background

Of the six tunnels that the Transport Agency manages in the state highway network, the Johnstone’s Hill

Twin Tunnels are relatively recent. The twin tunnels were opened in January 2009 to improve travel times

on the Auckland Northern Motorway between the Orewa turnoff and Puhoi by between 10 and 30 minutes.

As a toll road, they form part of State Highway 1 North (SH1N) and bypass the seaside townships of

Orewa, Hatfield’s Beach, Waiwera and the Wenderholm Regional Park.

The tunnels are two identical semi-circular uni-directional tubes, approximately 12m wide, 9m high and

380m long. They are built to carry two lanes each, plus a shoulder and an emergency pathway. Currently,

the southbound tunnel has two lanes open but the northbound tunnel has only one lane open due to the

merging of the traffic into a single lane immediately after the tunnel. The intention is to open the

northbound tunnel to two lanes of traffic once the Puhoi to Wellsford double-laning project has been

completed (scheduled for potential completion post 2015).

Based on the traffic volumes for 2010, the annual average daily traffic (AADT) for the Johnstone’s Hill

tunnel is approximately 14,000 vehicles per day, with the proportion of heavy duty commercial vehicles

(HCVs) at 9.5%.

The route is an important link for inter-regional traffic, including freight, between Northland and Auckland

as well as local traffic movements. The hourly weekday traffic counts suggest some influence of commuter

travel with broad peaks in the morning and in the evening. However, the hourly counts are significantly

higher for the weekend days when increased numbers of light duty vehicles travel to and from

destinations in the northern part of the Auckland region and Northland. Although HCVs use the road daily,

the number of these vehicles on weekend days is lower than on weekdays.

Due to safety considerations and the need to regularly access monitoring equipment for filter changes and

calibrations, the campaign was focused on the single lane northbound tunnel. Opting for the northbound

tunnel had advantages and disadvantages as follows:

• This tunnel had more free space available and installation of, and access to, monitoring equipment

is not expected to require a full shutdown.

• This tunnel was likely to be more prone to congestion, and therefore experience higher

contaminant concentrations, than the southbound tunnel. The northbound tunnel has already

recorded the highest levels of carbon monoxide to date since the tunnels have been in operation.

Using a tunnel with greater extremes in traffic flow conditions might make it easier to isolate the

factors that have the greatest impact on the in-tunnel air quality.

• The southbound tunnel, with two lanes of traffic, has a different traffic profile. This will not be

reflected in monitoring the northbound tunnel only.

1.2 Objectives

The objectives of the detailed monitoring undertaken at the Johnstone’s Hill tunnels were to:

• measure current in-tunnel air quality and compare it against the Transport Agency interim

standards

• determine the influence of key other parameters (eg traffic flow) on the in-tunnel air quality

• investigate various tunnel air quality monitoring methods and develop a standard approach for

future tunnel monitoring programmes

• identify key parameters to be used for future on-going management of in-tunnel air quality.


1.3 Agencies involved

Due to the comprehensive requirements of the detailed monitoring programme, a number of agencies

were involved in the collection of data as follows:

• Auckland Motorway Alliance (AMA)

• Institute of Geological and Nuclear Sciences (GNS)

• National Institute of Water and Atmospheric Research (NIWA)

• NZ Transport Agency

• Watercare (WSL)

The overall responsibility for coordinating the individual programme elements was undertaken by

Emission Impossible Ltd (EIL).

1.4 Report layout

This report is structured as follows:

• Chapter 2 outlines the equipment, sites and analysis techniques used in the monitoring

programme

• Chapter 3 presents the results

• Chapter 4 discusses the key findings

• Chapter 5 gives conclusions and recommendations

A full list of references and a glossary of terms are provided at the end of the report.


2. Methodology

This section summarises the methodological aspects of the report – including the monitoring method,

monitoring sites and analysis of results.

2.1 Site description

2.1.1 Tunnel purpose and location

The Johnstone’s Hill Twin Tunnels were opened in January 2009 to improve travel times on SH1 north of

Auckland. The tunnels bypass the seaside townships of Orewa, Hatfield’s Beach, Waiwera, and the

Wenderholm Regional Park (see figure 1 and figure 2) and reduce travel times by between 10 and 30

minutes. The section of SH1N between the Orewa turnoff and Puhoi is a toll road but vehicles are able to

travel free by using the old coastal route (SH17).

The Johnstone’s Hill Tunnels are open to all vehicular traffic.

Figure 1: Location of the Johnstone’s Hill Tunnels

1 km

N


Figure 2: Road map of the Johnstone’s Hill Tunnels

2.1.2 Geometry and ventilation

The tunnels are two identical semi-circular uni-directional tubes, approximately 12m wide, 9m high and

380m long, with a 1:100 gradient from each portal to the tunnel midpoint. The tunnels are 15m apart (see

figure 3) and are both built to carry two lanes each, plus a shoulder and an emergency pathway. The

northbound tunnel has only one lane open due to the merging of the traffic into a single lane after the

tunnel. The southbound lane has two lanes open.

Each tunnel has longitudinal ventilation, with each tunnel running three banks of paired jet fans. The fans

are triggered when carbon monoxide (CO) levels reach 30 parts per million (ppm).

200 m

N


Figure 3: View of the Johnstone’s Hill Twin Tunnels from the northern end

2.1.3 Traffic flow and fleet composition

Based on 2010 traffic data (from the ALPURT Telemetry Site – ref01N00388), the annual average daily

traffic (AADT) for the Johnstone’s Hill Tunnels is approximately 14,000 vehicles per day, with the

proportion of heavy duty vehicles (HCVs) at 9.5%.

The route is an important link for inter-regional traffic, including freight, between Northland and Auckland

as well as local traffic movements. The hourly weekday traffic counts in figure 4 suggest some influence of

commuter travel with broad peaks in the morning and in the evening. However, the hourly counts are

significantly higher (up to 45% more)13 for the weekend days when increased numbers of light duty

vehicles travel to and from destinations in the northern part of the Auckland region and Northland.

Although heavy commercial vehicles (HCVs) use the road daily, the proportion of these vehicles on

weekend days is much lower (down to 40% below) than on weekdays.

The posted speed limit is 80km/h.

13 Between 10am and 5pm on weekends (compared with week days).


Figure 4: Annual average daily traffic (AADT) flow for the Johnstone’s Hill Tunnels in 2010

2.1.4 Traffic monitoring

The nearest permanent traffic monitoring devices are four over height detectors which have traffic loops

connected to the system. Southbound, the first monitor (OHD101) is located just after the toll machines

turnaround (~1.2km before the tunnel entrance) and the second monitor (OHD102) is just after the

Waiwera turnoff (~250m before the tunnel entrance) but before the road splits into two lanes as shown in

figure 5. Northbound, the first monitor (OHD202) is on the SH1 motorway before the Grand Dr Exit (392)

(~7.6km before the tunnel entrance) and the second monitor (OHD201) is at the start of the Waiwera

Viaduct (~640m before the tunnel entrance) just before the traffic merges into one lane.

Unfortunately, none of these permanent sites is likely to be fully representative of the traffic flow

behaviour in the tunnel. Going south as the road widens to two lanes, traffic will tend to accelerate on

approach and through the tunnel so the OHD102 readings will be lower than the traffic speed through the

tunnel. Conversely, northbound traffic will tend to slow down going across the Waiwera viaduct as it

merges into one lane meaning the northbound tunnel speeds will be lower than recorded on OHD201.

Traffic flow behaviour, especially vehicle speed, impacts vehicle emissions. Even relatively small changes

in speed result in appreciable changes in emissions and therefore in-tunnel air quality. For example, a

typical vehicle travelling 5km/h faster than the posted 80km/h speed limit in the tunnel generates 2.8%

more oxides of nitrogen NOx and 4.2% more exhaust particulate per kilometre driven. On the other hand,

travelling 5km/h more slowly results in a 1.5% decrease in NOx and a 2.6% decrease in exhaust particulate.

Because the tunnels are toll roads, video surveillance is in place to record licence plates of vehicles using

the tunnels. These images are captured and stored by the Transport Agency, and therefore could be

interrogated to get more detailed fleet information.

0

200

400

600

800

1000

1200

1400

00 02 04 06 08 10 12 14 16 18 20 22 00

Hou

rly

Vehi

cle

Coun

t

Time of Day

Johnstone's Hill (northbound and southbound) TunnelsAnnual Average Traffic Flows for 2010

Weekday (all vehicles) Weekend (all vehicles) Weekday (heavy vehicles) Weekend (heavy vehicles)


Figure 5: General location of traffic monitoring devices in relation to Johnstone’s Hill Tunnels

2.1.5 Receiving environment

The tunnels are in a rural setting with very few residents nearby. There is a property adjacent to SH1

~300m north of the northern portal and scattered properties on Fowler Access Road which follows the

ridge of Johnstone’s Hill (see figure 2).

OHD201

OHD202

Johnstone’s Hill Tunnels

OHD102 OHD101


2.1.6 Meteorological conditions

The nearest permanent meteorological site is the Warkworth electronic weather station located at the

satellite station approximately 11.5km north of the tunnels (36.43435°S, 174.66766°E). Data from this site

is presented in figure 6.

The wind at the Warkworth electronic weather station site is measured at the top of a transmission tower

32m above ground level.

Given the relative distance and height of the Warkworth station, and the influence of local topography at

the tunnels, the Warkworth station is unlikely to be representative of the winds experienced at the tunnels.

Figure 6: Wind rose based upon hourly data from Warkworth EWS (January 2003 to December 2009

inclusive).

2.1.7 Previous monitoring

Prior to this monitoring campaign, there have been no reported measurements of air quality or visibility in

or near the Johnstone’s Hill Tunnels.


2.2 Parameters measured

Monitoring was undertaken by a variety of providers at the Johnstone’s Hill Tunnels in late March/early

April 2010 for a period of approximately three months. The parameters measured are shown in table 1.

Due to safety considerations and the need to regularly access monitoring equipment for filter changes and

calibrations, the campaign was focused on the single lane northbound tunnel. However, some parameters

were also able to be measured for the southbound tunnel (as highlighted in bold in table 1).

Table 1: Parameters measured at Johnstone’s Hill Twin Tunnels for March to July 2010

Parameter Location Campaign instrument Permanent instrument

Air flow* In tunnel

(at 25m in from exit)

Flowsic 200

air flow meter (AMA)

Carbon monoxide

CO*

In tunnel


Continuous

CO analyser (WSL)

Vicotec 412

CO sensor (AMA)

Fine particulate

PM10

In tunnel


Continuous beta

attenuation monitor (GNS)

Jet fan

operation*

In tunnel

(at 80m in from entrance and

from exit)

In tunnel

Sensor (AMA)

Nitrogen dioxide

NO2

In tunnel


Continuous

NO2 analyser (WSL)

7x In tunnel and 10x external

(from 200m S of entrance to

200m N of exit)

Passive

samplers (WSL)

Traffic counts

%HCVs

and speed*

At both tunnel entrances

Golden River marksman 680

traffic counter connected to

dual inductive loops (AMA)

Wind speed

and direction

External

(on top of the hill in Fowler

Access Rd)

Anemometer

on 6m mast (WSL)

* Parameters measured for both the northbound and southbound tunnels

AMA – Auckland Motorway Alliance

WSL – Watercare Services Laboratory

GNS – Institute of Geological and Nuclear Sciences


2.2.1 Permanent monitoring

The Johnstone’s Hill Tunnels have permanent in-tunnel sensors installed as part of the ventilation control

system measuring CO, air flow and jet fan operation. These sensors provide online ‘live’ data to the tunnel

operator at approximately 1-minute intervals but are not continuously logged. At any time a 3-month

running record is available but this is updated and over-written each day.

During the campaign, data from the in-tunnel sensors were retrieved periodically by the Auckland

Motorway Alliance (AMA) and stored separately to maintain a data record for the whole monitoring period.

Due to a system problem, data were lost at the beginning of the campaign for the period of 26 March to

7 April 2010 inclusive (which unfortunately, incorporated the Easter period).

(i) Carbon monoxide

A Vicotec 412 CO sensor is located approximately 30m from the exit of each tunnel. The CO sensor

measures concentrations (as ppm) in the tunnel using an infrared beam. When CO level reach 30ppm the

jet fans are triggered.

(ii) Air flow

Permanent Flowsic 200 air flow sensors are located 25m from the exit of each tunnel. These sensors use

ultrasonic technology to measure air velocity in m/s (which can be positive or negative depending on

whether the flow is in or against the direction of the tunnel traffic).

(iii) Jet fan operation

Three sets of paired jet fans are located in each tunnel - at approximately 80m from the entrance, 80m

before the exit, and at the midpoint. Each fan sends a signal indicating its state of operation as follows:

11 Stopped 130 Starting forward 131 Starting reverse 134 Run up forward 135 Run up reverse 129 Forward 5 Reversing

10 Spin down

2.2.2 Campaign monitoring

The Transport Agency commissioned several providers to undertake specific campaign monitoring during

the monitoring period to supplement the permanent in-tunnel data and better understand the factors

influencing the in-tunnel air quality. The campaign monitoring comprised:

• continuous monitoring of CO and NO2 to compare against readings from the in-tunnel sensors and

assess against in-tunnel air quality guidelines (by Watercare Services Ltd)

• passive sampling of NO2 to indicate the spatial distribution of concentrations in and around the

tunnel (by Watercare Services Ltd)

• continuous monitoring and source apportionment of particulate to establish the major

sources/parameters contributing to in-tunnel air quality (by Institute of Geological and Nuclear

Sciences)


• continuous monitoring of wind speed and wind direction to assess the effect of external

meteorology on in-tunnel air flow and concentrations (by Watercare Services Ltd)

• specific traffic monitoring to provide actual counts, %HCVs and average speeds in the tunnel

during the monitoring period (by Auckland Motorway Alliance).

The following subsections discuss the campaign monitoring in more detail.

The general location of the campaign monitoring sites for continuous measurement of gaseous pollutants

(CO and NO2) and meteorology (wind speed and wind direction) are shown in figure 7.

Figure 7: Location of the sites for continuous gaseous monitoring (CO, NO2) and continuous

meteorology monitoring (wind speed, wind direction)

(i) Continuous CO and NO2 monitoring

Continuous monitoring of CO and NO2 was carried out from 30 March to 13 July 2010 at a location 30m

inside the northbound exit of the Johnstone’s Hill Tunnels as shown in figure 8. The inlet was connected

to monitoring equipment located in a mobile trailer parked just outside the north end of the tunnels as

shown in figure 9.

Carbon monoxide was measured using AS 3580.7.1 – 1992 Method 9.1: Determination of carbon

monoxide – direct reading instrumental method using an Ecotech model 9830. The instrument is an

infrared absorption gas analyser which continuously measures carbon monoxide.

Nitrogen dioxide was measured using AS 3580.5.1-1993 Method 5.1: Determination of oxides of nitrogen

– chemiluminescence method. The instrument was a Teledyne API model 200E which continuously

measures oxides of nitrogen (NOx), which include NO

2.


Figure 8: Location of the inlet for the continuous CO and NO2 monitoring

Figure 9: Location of the trailer which housed the continuous CO and NO2 monitoring equipment

(ii) Passive NO2 sampling

Nitrogen dioxide was also measured at 50m intervals at five locations before the tunnel (travelling

northbound), six locations inside the tunnel and five locations after the tunnel (travelling northbound) at

monthly intervals using passive samplers. These monitoring locations are shown in figure 10.

Passive NO2 samplers consist of an acrylic or PTFE tube 700mm long and 10mm internal diameter with the

ends machined to take close fitting polythene caps. Each tube contains two stainless steel mesh discs,


coated with triethanolamine. Nitrogen dioxide is determined spectrophotometrically by a variation of the

Saltzman reaction.

Passive samplers were exposed for 1-month periods, from 29 March and 26 June 2010 (three separate

monthly periods in total).

Figure 10: Location of passive NO2 samplers


(iii) Particulate monitoring

Fine particulate (PM10

) was measured continuously between 29 April and 14 July 2010, using a beta

attenuation monitor located approximately 25m from the exit of the northbound tunnel. The PM10

sampling equipment was contained in a pillar box bolted to the western wall of the tunnel as shown in

figure 11.

Figure 11: Pillar box housing the particulate monitoring equipment inside the tunnel

Source apportionment was carried out at the same location using a Streaker sampling system as shown in

figure 12. This collected discrete 3-hourly particulate samples in two size fractions (PM2.5

and PM2.5-10

)

through all of June 2010.

Figure 12: Streaker sampling system (shown left) with a typical sample filter showing hourly particle samples collected as discrete bands (shown right)

1st sample


PM10

concentrations were derived from the beta attenuation monitor and elemental concentrations were

provided by ion beam analysis.14 Receptor modelling was then performed using two multivariate analysis

approaches:

• Principal components analysis was used to characterise the p variables (elemental concentrations)

in sample X in terms of a small number m of common factors F in order to examine relationships

between the variables and provide an initial estimate of the number of factors (contributing

particulate matter sources) present.

• Positive matrix factorisation (a linear least-squares approach) was applied to the multivariate data

to provide source profiles (elemental composition of particulate matter from each of the sources)

and apportion per-sample PM10

mass concentrations (to the various sources).

(iv) Meteorology monitoring

The meteorological monitoring station was located in a 50m wide clearing, 60m east of the tunnels on

Fowler Access Road as shown in figure 13.

Measurements of wind speed and wind direction were measured at 6m above ground level in accordance

with AS 2923 – 1987 Ambient air – guide for measurement of horizontal wind for air quality applications.

The instruments continuously measured wind speed and wind direction from 30 March to 13 July 2010.

Figure 13: Meteorological monitoring station on Fowler Access Road

14 A full description of ion beam analysis and receptor modelling is provided in GNS (2011)


(v) Traffic monitoring

Traffic monitoring was undertaken from 26 March to 1 July 2010 (inclusive) using Golden River Marksman

680 traffic counters connected to dual inductive loops, which were installed at both tunnel entrances to

ensure capture of representative traffic flow measurements.

The traffic counters logged 15-minute counts broken down into four axle lengths:

• <5.5m, <11m, <17m and 17m

as well as 12 average speed bins:

• <20km/h, <30km/h, <40km/h, <45km/h, <50km/h, <55km/h, <60km/h, <70km/h, <80km/h,

<90km/h, <100km/h and >100km/h

The axle length data were used to calculate the fraction of heavy duty commercial vehicles (%HCVs) in a

15-minute period – basically the number of vehicles with axle lengths greater than 5.5m over the total

number of vehicles.

The counts in each of the average speed bins were pro-rated by the speed to provide an overall average

speed for all vehicles passing through the tunnel in a 15-minute period.

All traffic monitoring was conducted in accordance with the NZTA’s SM052 Traffic monitoring for state

highways.

Note: these loops were left in place at the end of the campaign and would be able to be reconnected to a

data logger for any future monitoring undertaken at Johnstone’s Hill.

2.3 Assessment criteria

2.3.1 In-tunnel air quality

Table 2 presents the interim Transport Agency in tunnel air quality standards for CO and NO2. These apply

in tunnel and are designed to protect both workers and the general population (as specified in table 2).

For vehicles travelling at the speed limit of 80 km/h through the Johnstone’s Hill Tunnel, it would take

approximately 14 seconds to traverse the 300m tunnel length.

Table 2: Interim Transport Agency in-tunnel air quality standards

Air pollutant Limit Averaging period Protection Application

CO

200ppm 15-minute Workplace

Design and compliance

monitoring standard 30ppm 8-hour Workplace

87ppm 15-minute General population

NO2 1.0ppm 15-minute

Workplace and general

population Design standard only


2.3.2 External air quality

Table 3 presents ambient air quality guidelines and standards that apply to outdoor air (ie, outside the

tunnel) in New Zealand. It should be noted that these standards and guidelines do not apply to the short-

term exposure periods that vehicle occupants or workers may be exposed to in a tunnel.

The air quality criteria presented in table 3 are sourced from the national ambient air quality guidelines15,

the national environmental standards for air quality16 and the World Health Organisation17.

Table 3: Various ambient air quality standards and guidelines

Air pollutant Limit Averaging period Protection Standard

CO 30mg/m3 1-hour General population AAQG

10mg/m3 8-hour General population AQNES

NO2

200µg/m3 1-hour General population AQNES

100µg/m3 24-hour General population AAQG

40µg/m3 annual General population WHO

PM10

50µg/m3 24-hour General population AQNES

20µg/m3 annual General population AAQG

2.4 Data processing/analysis

2.4.1 Permanent monitoring

The Vicotec 412 CO sensor (northbound tunnel) was last calibrated during commissioning (20-24 October

2008). The operation manual does not state how often maintenance or calibration is required.

The Flowsic 200 air flow meter (northbound tunnel) was last calibrated during commissioning (20-23

October 2008). The operation manual states that maintenance (cleaning) is required every six months to

five years, depending on the individual installation and the model device installed. No information is

provided on the need, or otherwise, of calibration.

Permanent monitoring data (collected continuously and recorded as 1-minute averages) was aggregated

into base 15-minute fixed averages for further review.

15 MfE (2002). Ambient air quality guidelines, 2002 Update, Air Quality Report No 32 prepared by the Ministry for the Environment and the Ministry of Health, May 2002 16 Resource Management (National Environmental Standards for Air Quality) Regulations 2004 17 WHO (2006). Air quality guidelines global update 2005: Particulate matter, ozone, nitrogen dioxide, and sulphur dioxide, World Health Organisation, October 2006


2.4.2 Gaseous (CO and NO2) monitoring

Watercare Laboratory Services (instrumental campaign monitoring for CO and NO2) is accredited by

International Accreditation New Zealand for the standard methods employed (AS 3580.7.1:1992 and AS

3580.5.1:1993). The station was environmentally-controlled ensuring instrument requirements and

relevant standard requirements were within specifications. Data return was excellent (greater than 95%)

for all parameters monitored.

Passive samplers were analysed by Staffordshire County Council Scientific Services in the United Kingdom.

A travel blank was transported and analysed with the samplers to flag potential contamination issues

(none were found). All passive sampling was undertaken in accordance with the Transport Agency’s

operating manual18.

All pollutant concentrations were calculated at New Zealand standard conditions of temperature (0°C) and

pressure (1atm).

2.4.3 Particulate monitoring

The E-BAM (Met One Instruments Inc.) used to monitor PM10

was operated and calibrated in accordance

with the Operation Manual (E-BAM 9800 RevK). During the Johnstone’s Hill Tunnel campaign monitoring

the E-BAM (Serial no. K10255) was calibrated and audited on start-up and monthly thereafter. Specific

checks include leak tests, sample flow audits (using a Sensidyne Gillian 'Gilibrator 2' primary standard flow

calibrator), self-test diagnostics and membrane tests for PM mass calibration. PM10

data collected by the E-

BAM was vetted for anomalies and data collected during calibration was removed from the final dataset.

Diagnostic and statistical checks on the receptor modelling are reported in full in GNS (2011).

18 NZTA (2012a). Ambient air quality (nitrogen dioxide) monitoring programme – operating manual 2012/13, prepared by Watercare Services Ltd and Emission Impossible Ltd for NZ Transport Agency, September 2012.


3. Results

The results in this section are presented by in-tunnel ventilation, in-tunnel traffic, in-tunnel air quality,

meteorology and source apportionment.

3.1 In-tunnel ventilation

3.1.1 Air flow

Summary air flow data for both tunnels from the period of monitoring are given in figure 14 (northbound

tunnel) and figure 15 (southbound tunnel) as 1-hour averages.

Negative air speed, which appears repeatedly throughout figures 14 and 15, appears to indicate that air is

moving backwards and forwards in both tunnels. In other words, the northbound tunnel experiences both

northbound and southbound air flow movement, as does the southbound tunnel.

Negative data occurred often, but not always, in the early hours of the morning. This may reflect the

influence of external wind speeds and low vehicular traffic in the absence of any ventilation (the jet fans

were off for the entire duration of campaign monitoring). Alternatively, the sensors may need

recalibrating. It appears the sensors were last calibrated in October 2008.

Figure 14: Air flow monitoring (northbound tunnel)

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-4

-2

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Air

velo

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(m/s

)

Johnstone's Hill (northbound) TunnelAir Speed (1 hour average)


Figure 15: Air flow monitoring (southbound tunnel)

3.1.2 Jet fan operation

The jet fans were not triggered (so did not operate at all) during the period of monitoring between

30 March–13 July 2010.

3.2 In-tunnel traffic

In-tunnel traffic over the campaign monitoring period is presented in figure 16. The flow of heavy

commercial vehicles is consistent on weekdays, dropping on weekends and public holidays. Conversely,

the flow of passenger cars peaks consistently each Friday and on the Friday and Saturdays of public

holiday weekends.

-8

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-4

-2

0

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4

6

8

07-Apr 21-Apr 05-May 19-May 02-Jun 16-Jun 30-Jun 14-Jul

Air

velo

city

(m/s

)Johnstone's Hill (southbound) Tunnel

Air Speed (1 hour average)


Figure 16: In-tunnel traffic during the period of campaign monitoring

3.3 In-tunnel air quality

3.3.1 Carbon monoxide

The results of in-tunnel monitoring for CO (both campaign and permanent) are presented in figure 17 (15-

minute average) and figure 18 (8-hour average).

All recorded levels of CO were well below the relevant Transport Agency interim in tunnel air quality

guidelines.

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6000

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14000

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raff

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ll ve

hicl

es)

Johnstone's Hill (northbound) TunnelDaily Traffic 31 Mar - 1 Jul 2010

All vehicles Heavy commercial vehicles

Easter (Good Friday)

Queens Birthday


Figure 17: In-tunnel CO (15-minute average), March – July 2010

Figure 18: In-tunnel CO (8-hour rolling average), March–July 2010

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Carb

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(ppm

, 15-

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ute

aver

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Johnstone's Hill (northbound) TunnelCarbon monoxide (ppm, 15-minute average, Mar - Jul 2010)

Vicotec 412 (Permanent) Ecotec 9830 (Campaign) NZTA In Tunnel Guideline

NZTA In Tunnel guideline (general population) = 87 ppm

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35


Carb

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onox

ide

(ppm

, 8-h

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Johnstone's Hill (northbound) TunnelCarbon monoxide (8-hour average, Mar - Jul 2010)

Vicotec 412 (Permanent) Ecotec 9830 (Campaign) NZTA In Tunnel Guideline

NZTA In Tunnel guideline (workers) = 30 ppm


3.3.2 Nitrogen dioxide

Nitrogen dioxide was measured both continuously (instrumental monitoring) and at monthly intervals

(passive sampling). Continuous NO2 monitoring is presented in figure 19 (15-minute average), with

monthly sampling presented in figure 20.

Figure 19: In-tunnel NO2 (15-minute average), March – July 2010

Figure 20: Monthly NO2 inside and outside northbound tunnel, April – June 2010

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Johnstone's Hill (northbound) Tunnel Nitrogen dioxide (ppm, 15-minute average, Mar - Jul 2010 )

NZTA In Tunnel guideline (general population) = 1 ppm

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Johnstone's Hill (northbound) Tunnel Nitrogen dioxide (µg/m3, monthly average, Apr - Jun 2010)

April

May

June

Inside Tunnel


A comparison of both methods is given in figure 21 and shows that the passive method measures slightly

higher than the continuous method (on average, 16% higher). This finding is in keeping with the results of

the Transport Agency’s national passive monitoring programme which found that passive samplers over-

read by 27% on average versus co-located continuous monitors19.

Figure 21: Passive and continuous in-tunnel NO2, April – June 2010

All recorded levels of NO2 inside the tunnel were well below the relevant NZTA interim in-tunnel air quality

guidelines. However, elevated concentrations were recorded just outside the tunnel exit (site AUC165)

with monthly averages of 43.2µg/m3 in May, 40.2µg/m3 in June and 34.8µg/m3 in July. Although close to

the World Health Organisation annual NO2 guideline of 40µg/m3, the AUC165 results for three months

cannot be directly compared to a guideline which covers 12 months. NO2 concentrations vary seasonally

with winter (June, July and August) concentrations nearly twice those of summer (December, January and

February) levels20.

NIWA has previously undertaken work to seasonally de-trend monthly passive data and developed

adjustment factors for estimating annual average concentrations based on monthly means21. In this work,

the adjustment factors are 0.810 for April, 0.748 for May and 0.742 for June. Applying these factors to the

AUC165 data yields an annual average estimate in the range of 25.8 to 35.0 µg/m3. However, it is not

possible to say definitively whether the WHO annual NO2 guideline would have been exceeded had the

monitoring continued for a full 12 months.

19 NZTA (2012b). Ambient air quality (nitrogen dioxide) monitoring network – Annual report 2007 to 2011, NZ Transport Agency, September 2012. 20 Ibid. 21 NIWA (2010c). A regression approach to assessing urban NO

2 from passive monitoring – Application to the Waterview

Connection. NIWA Report AKL-2010-023 prepared for NZ Transport Agency, June 2010.

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April 2010 May 2010 June 2010

Mon

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Johnstone's Hill (northbound) TunnelContinuous and Passive Nitrogen Dioxide Monitoring

Continuous Monitoring Passive Monitoring


3.3.3 Particulate matter

PM10

monitoring is presented in figure 22 (15-minute average) and figure 23 (24-hour average).

A peak in PM10

concentrations is evident in the 15-minute and 24-hour averages (around midday on 16

May 2010). This may have been due to dust generating activities (maintenance or roadworks) in the tunnel

environs but was unable to be confirmed.

Figure 22: In-tunnel PM10

(15-minute average), March – July 2010

The Transport Agency has no in-tunnel guidelines for PM10

. However, ambient (outdoor) PM10

is regulated

by a national environmental standard (NES) which sets an upper limit of 50µg/m3 for a 24-hour average.

In-tunnel concentrations were well within this NES during the monitoring period.

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350

29-Mar 08-Apr 18-Apr 28-Apr 08-May 18-May 28-May 07-Jun 17-Jun 27-Jun 07-Jul

PM10

15 m

inut

e av

erag

e (µ

g m

-3)

Johnstone's Hill (northbound) Tunnel PM10 (µg/m3, 15-minute average, Mar-Jul 2010)


Figure 23: In-tunnel PM10

(24-hour average), March – July 2010

3.4 Meteorology The predominant wind directions during the monitoring period in the Johnstone’s Hill area were from the

north north-west, and east south-east as shown by the wind rose in figure 24. This confirms the site

meteorology is significantly different to that measured at the nearest permanent station at Warkworth

where winds are predominantly from the west south-west and the west (refer figure 6).

The predominant north north-westerly measured in the Johnstone’s Hill area also aligns with the tunnel

direction.

Figure 24: Wind rose for April-July 2010

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50

31-Mar 14-Apr 28-Apr 12-May 26-May 09-Jun 23-Jun 07-Jul

PM10

(µg/

m3 ,

24-

hour

ave

rage

)Johnstone's Hill (northbound) Tunnel

PM10 (µg/m3, 24-hour average, Mar-Jul 2010)

NES (outdoors) = 50 µg/m3

NORTH

SOUTH

WEST EAST

4%

8%

12%

16%

20%

WIND SPEED (m/s)

>= 10.0

7.0 - 10.0

5.0 - 7.0

3.0 - 5.0

2.0 - 3.0

1.0 - 2.0

Calms: 26.42%


3.5 Source apportionment

Six primary sources were found to contribute to in tunnel particulate matter concentrations:

• Light duty vehicles

• Heavy duty commercial vehicles

• Smoky vehicles

• Re-suspended road dust

• Biomass (wood) burning

• Marine aerosol (sea salt)

As would be expected, the predominant sources of PM10

in the tunnel were related to vehicles. Figure 25

presents the average source contributions to PM10

. Heavy duty commercial vehicles were responsible for

66% of the vehicle-related PM10

(excluding the road dust component) despite contributing only 10% of total

traffic volume. Heavy duty vehicles are almost exclusively powered by diesel. Light duty vehicles (90% of

traffic volume), mainly petrol-fuelled, contributed 17% of the vehicle related PM10

.

Figure 26 presents PM10

from motor vehicles aggregated over the monitoring period.

Figure 25: Average source contributions to in tunnel PM10

(June 2010)

Figure 26: Aggregate time-series of vehicle source contributions to PM

10 mass in Johnstone’s Hill Tunnel

(light duty vehicles, heavy duty commercial vehicles, smoky vehicles and road dust)

Light duty vehicles

7%

Heavy commercial

vehicles25%

Smoky vehicles

7%

Road dust28%

Biomass burning

4%

Marine aerosol29%

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ass

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(µg

m-3

)


4. Key findings

4.1 Diurnal trend

The continuous CO and NO2 results both peaked in the middle of the day as shown in figure 27. This

figure presents results for 3 April 2010 (which recorded the maximum CO levels for the monitoring

period) but the trends was typical of all days monitored.

This trend matches vehicle traffic as shown in figure 28 which plots CO and traffic counts for the same

day. However, the same could not be said of PM10

which displayed no obvious temporal trend either daily

or when comparing week days with weekends as shown in figure 29.

Figure 27: Daily trend in CO and NO2 concentrations for 3 April 2010

Figure 28: Comparison of CO with traffic count for 3 April 2010

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(ppm

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3 April 2010

Johnstone's Hill (northbound) TunelCarbon monoxide (15-minute average, 3 April 2010)

CO NO2

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Johnstone's Hill (northbound) TunnelCarbon monoxide and Traffic (3 April 2010)

CO Traffic (all vehicles)


Figure 29: Average hourly PM10

on week days and weekends over monitoring period

4.2 Holiday traffic

The period of monitoring covered two holiday weekends, during which northbound traffic increased

significantly as shown in figure 17. Because monitoring was carried out in the northbound tunnel, the

analysis focuses on Good Friday when traffic heading north increased.

Surprisingly, the increased (northbound) holiday traffic during these periods was not reflected in increased

levels of CO, NO2 or PM

10. Figure 30 plots CO with hourly traffic over the Easter period and there is no clear

correlation. This may be a result of increased air flow in the tunnel, however, the air flow data for this

period were lost and this cannot be confirmed.

Figure 30: Carbon monoxide levels over Easter weekend, 2010

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25

00 02 04 06 08 10 12 14 16 18 20 22 00

Hou

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PM10

(µg/

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Johnstone's Hill (northbound) TunnelAverage hourly PM10 (29 Mar-14Jul 2010)

Week days Weekends

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ount

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vehi

cles

)

Johnstone's Hill (northbound) TunnelEaster weekend 2010

Traffic CO

Good Friday


Similarly, pollutant levels (CO, NO2 or PM

10) did not increase during the increased northbound traffic over

Queens Birthday weekend. Available data suggest increased air flow through the tunnel at this time and

this is likely to have offset elevated levels as shown in figure 31.

Figure 31: Carbon monoxide levels over Easter weekend, 2010, in relation to traffic and air flow

4.3 Operational monitoring of in-tunnel parameters

4.3.1 Tunnel ventilation

The tunnel air flow sensors appear to indicate prolonged periods of negative air speed. In other words, the

northbound tunnel experiences both northbound and southbound air flow movement, as does the

southbound tunnel. This may reflect the influence of external wind speeds and low vehicular traffic in the

absence of any ventilation (the jet fans were off for the entire duration of campaign monitoring).

(Alternatively, the sensors may need recalibrating as discussed below).

4.3.2 Sensor performance

Data from existing operational monitoring of CO and air flow is limited and could be improved.

Whilst these sensors provide online ‘live’ data to the tunnel operator, they are not continuously logged. At

any time a three-month running record is available but this is updated and over-written each day. This is

why air flow data were not available to investigate any correlation between pollutant levels and traffic

count during Easter.

The permanent, in tunnel CO sensor appears to be suffering from upwards drift and requires recalibration.

The sensor consistently over-read by 5ppm relative to the continuous campaign monitor (which was

calibrated daily) and appears to be increasing by around 0.5ppm per month. This is shown clearly in figure

32 (8-hour average). According to available records, the CO sensor was last calibrated during installation

in October 2008. (This is likely to also be the case for the CO sensor in the southbound tunnel).

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03-Jun 04-Jun 05-Jun 06-Jun 07-Jun 08-Jun 09-Jun 10-Jun 11-Jun

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(ppm

), (+

ve) A

ir fl

ow (m

/s)

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Traf

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(all

vehi

cles

)

Johnstone's Hill (northbound) TunnelQueens Birthday weekend 2010

Traffic CO (+ve) Air Flow

Friday / Saturday


Figure 32: In-tunnel CO (8-hour rolling average), March – July 2010

Note: since the tunnel monitoring campaign ended, both the northbound and southbound in-tunnel CO

sensors have been repaired and re-calibrated several times22. The southbound sensor was fixed and both

sensors re-calibrated on 4 August 2011. The northbound sensor was fixed and both sensors re-calibrated

on 14 August 2012. In both instances, the stepper motors had failed.

Both sensors are now being serviced annually with more regular calibration checks being undertaken.

4.4 In-tunnel dispersion

Local meteorological monitoring indicates that the predominant wind direction (at least for the period

March to July 2010) is from the north north-west, which aligns with the direction of the tunnels. As a

result, local winds have the potential to impact on in-tunnel air flow and subsequent dispersion of traffic

emissions.

External wind speed does appear to impact in-tunnel air flow as shown in figure 33. The impact of

external wind speed on in-tunnel dispersion is, however, less clear. Plots of PM10

and CO with external

wind speed (figures 34 and 35 respectively) show little correlation.

In practice, it is likely that a combination of in-tunnel air flow, external wind speed, traffic volume and

traffic composition all impact on in-tunnel pollutant levels.

22 T Sullivan (2013) of Auckland Motorway Alliance, pers. comm., 4 February

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Carb

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(ppm

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vera

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Johnstone's Hill (northbound) TunnelCarbon monoxide (8-hour average, Mar - Jul 2010)

Vicotec 412 (Permanent) Ecotec 9830 (Campaign)


Figure 33: External wind speed and in-tunnel air flow (June, 2010)

Figure 34: External wind speed and in-tunnel PM10

(June, 2010)

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01-Jun 06-Jun 11-Jun 16-Jun 21-Jun 26-Jun 01-Jul

(Pos

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d (m

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Johnstone's Hill (northbound) TunnelExternal wind speed and in tunnel air flow (June 2010)

Air Speed Wind Speed

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Johnstone's Hill (northbound) TunnelExternal wind speed and in-tunnel PM10 (June 2010)

PM10 External wind speed


Figure 35: External wind speed and in-tunnel CO (June, 2010)

4.5 External air quality

Monthly sampling of NO2 was undertaken at 50m intervals at five locations before the tunnel (travelling

northbound), six locations inside the tunnel and five locations after the tunnel (travelling northbound)

using passive samplers. The results indicate that levels of NO2 increase along the length of tunnel and

remain slightly elevated (compared with pre-tunnel levels) immediately beyond (ie, within 200m of) the

tunnel exit.

There was, however, significant deviation in levels recorded in the tunnel centre, the entrance and the exit.

These are likely to reflect the changing air flow in the tunnels (refer section 4.4).

4.6 Heavy duty vehicles

Whilst heavy duty vehicles average only 10% of weekday traffic through the tunnels (and less during

weekends), they appear to disproportionately impact levels of some pollutants.

Typically light duty petrol vehicles emit higher quantities of CO per kilometre driven whereas heavy duty

diesel vehicles emit higher quantities of PM10

and NO2 per kilometre. Figures 36 and 37 show the

relationships between the pollutant concentrations measured in the tunnel and vehicle counts for light

duty and heavy duty vehicles, respectively. These figures confirm that CO concentrations are more

strongly correlated with light duty vehicles (R2=0.44 vs 0.11) whereas NO2 concentrations are slightly more

strongly correlated with heavy duty vehicles (R2=0.40 vs 0.33).

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(Pos

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peed

(m/s

)

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-hou

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, ppm

)

Johnstone's Hill (northbound) TunnelExternal wind speed and in-tunnel CO (June 2010)

CO External wind speed


Neither vehicle weight class has a strong influence on total PM10

concentrations (due to the presence of

other PM10

sources) but the source apportionment shows that 66% of the vehicle exhaust-related PM10

is

attributed to heavy duty vehicles alone.

Figure 36: Correlation between pollutant concentrations measured in the tunnel and light duty

vehicle counts (March - June, 2010)

Figure 37: Correlation between pollutant concentrations measured in the tunnel and heavy duty

vehicle counts (March - June, 2010)


As a further illustration, figure 38 presents in tunnel levels of NO2 and PM

10 with hourly counts of heavy

duty vehicles. In general in-tunnel levels of NO2 and PM

10 track heavy duty vehicle counts reasonably well

but there are also days when pollutant levels remain elevated and heavy duty vehicle traffic is low. This is

most likely due to a combination of increased other (light duty) traffic and low air flow and/or in tunnel

ventilation.

Figure 38: Comparison of in-tunnel NO2 and PM

10 with heavy duty vehicle counts (June, 2010)

0

20

40

60

80

100

120

140

0

20

40

60

80

100

120

140

160

180


Hou

rly

PM10

and

NO

2(µ

g/m

3 )

Hou

rly

Hea

vy D

uty

Vehi

cle

Coun

t

Johnstone's Hill (northbound) TunnelPM10 , NO2 and Heavy Duty Vehicles (June 2010)

Heavy Vehicles PM10 NO2


5. Conclusions and recommendations

5.1 Conclusions

5.1.1 Compliance with standards and guidelines

In-tunnel air quality

All pollutants (CO, NO2 and PM

10) measured inside the tunnel were well within the Transport Agency

interim in tunnel air quality guidelines.

External air quality

Levels of NO2 measured using (passive) diffusion tubes just outside the northern tunnel exit were close to

the World Health Organisation annual average guideline for NO2 (40 µg/m3). However, monthly levels (43,

40 and 35 µg/m3) for a period of only three months cannot be compared directly with the annual guideline

which covers 12 months. Winter (June, July, August) NO2 levels are typically twice those of summer

(December, January, February) levels.

Applying adjustment factors developed for NIWA to seasonally de-trend monthly passive data yields an

annual average estimate in the range of 25.8 to 35.0 µg/m3. However, it is not possible to say definitively

whether the WHO annual NO2 guideline would have been exceeded just outside the tunnel exit had the

monitoring continued for a full 12 months. It should be noted that the nearest potentially sensitive

receptors (ie residences) are located more than 300m away from either portal; therefore it is unlikely that

any person is being exposed to ‘high’ NO2 levels for a year.

The meteorological monitoring confirmed that meteorology at the Johnstone’s Hill tunnels is different to

that of the nearest permanent station at Warkworth. The predominant wind direction (north north west)

aligns with the direction of the tunnel.

5.1.2 Disproportionate impact of heavy duty vehicles

Whilst heavy duty vehicles average only 10% of weekday traffic through the tunnels (and less during

weekends), they appear to disproportionately impact levels of some pollutants.

CO concentrations are more strongly correlated with light duty vehicles (which are predominantly petrol-

fuelled) whereas NO2 concentrations are slightly more strongly correlated with heavy duty vehicles (almost

exclusively diesel-fuelled).

Neither vehicle weight class has a strong influence on total PM10

concentrations (due to the presence of

other PM10

sources) but the source apportionment shows that 66% of the vehicle exhaust-related PM10

is

attributed to heavy duty vehicles alone.


5.2 Recommendations

5.2.1 Key parameters for future management

Data logging

Currently sensor data (air flow, CO and jet fan operation) are over-written each day. It is recommended

that this information be continuously logged instead and permanently stored or archived as 15-minute

averages.

Sensor calibrations

The permanent, in tunnel CO sensors require recalibration. Currently, the northbound tunnel sensor is

drifting upwards by about 0.5ppm per month (refer figure 32). If this drift continues, there is a risk that

the sensor will erroneously measure levels in excess of the in-tunnel limit for CO (for workers) and hence

trigger the jet fans. Based on current rate of drift, this may happen by May 2014. It is likely that the sensor

in the southbound tunnel is also drifting upward and should also be checked as soon as possible.

The permanent, in tunnel air flow sensors may also need recalibrating. Negative air speed (refer figures 14

and 15) suggests the air is moving backwards and forwards in both tunnels. If so, this requires further

investigation as it may impact on effective tunnel ventilation in the event of the jet fans being operated.

It appears that all sensors were last recalibrated during installation in October 2008.

Note: since the tunnel monitoring campaign ended, both the northbound and southbound in-tunnel CO

sensors have been repaired and re-calibrated several times23. Both sensors are now being serviced annually

with more regular calibration checks being undertaken.

5.2.2 Design suggestions for future tunnel monitoring campaigns

The Johnstone’s Hill Tunnels are relatively short (~380m) and appear to be well-ventilated with low to

moderate levels of traffic (around 14,000 vehicles per day) compared to other tunnels in the state highway

network. For example, Lyttelton tunnel is 1,945m long and carries around 11,000 vehicles per day.

Whilst in-tunnel levels of CO correlate reasonably well with light duty vehicles and NO2 with heavy duty

vehicles, the correlations are not strong with and between all pollutants and all vehicle weight classes.

Carbon monoxide did not correlate with either PM10

or NO2. These findings indicate that future monitoring

campaigns in other tunnels will need to monitor for all three pollutants simultaneously. This will be

particularly true for longer tunnels with more traffic and/or less ventilation. Campaign monitoring is

recommended on a five-yearly basis.

Similarly, the campaign showed the importance of on-site meteorological and on-site traffic monitoring. It

is therefore recommended that future monitoring campaigns similarly include on-site measurements of

both to maximise the understanding of all of the factors that influence in-tunnel and surrounding air

quality.

Passive sampling was useful in ascertaining the spatial distribution of NO2 levels before, inside and after

the tunnel. Whilst measured levels were slightly over-estimated in comparison with continuously measured

levels (at the same location), passive sampling appears to be a cost effective method for investigating

23 T Sullivan (2013) of Auckland Motorway Alliance, pers. comm., 4 February


spatial distribution. There would be value in running a 12 month passive sampling programme around the

tunnel portals to better understand how levels compare with the WHO annual NO2 guideline.

Internationally, tunnel monitoring campaigns are also employed to research other aspects of vehicle

emissions management such as:

• verifying vehicle emission factors and predicted emissions from emission prediction models, such

as the Vehicle Emission Prediction Model (VEPM24)

• developing new emission factors for sources such as road dust, which is currently poorly

understood in New Zealand

• assessing air pollution dispersion from tunnel portals using a combination of monitoring and

modelling

• collecting concentrated samples for investigating the toxicity of vehicle emissions (especially

those resulting from diesel vehicles25)

A well-designed and well-coordinated future tunnel monitoring campaign could address most (if not all) of

the recommendations in this section and lead to improved design/management of tunnels in the state

highway network as well as furthering a better understanding of general vehicle emissions in New

Zealand.

24 See the NZ Transport Agency’s transport and air quality website (air.nzta.govt.nz) for additional information on VEPM, including the model itself and the Users’ Guide. 25 The International Agency for Research on Cancer, which is part of the World Health Organisation, classified diesel engine exhaust as carcinogenic to humans on 13 June 2012.

http://www.air.nzta.govt.nz/


6. References

GNS (2011). Concentration, composition and sources of particulate matter in the Johnstone’s Hill tunnel,

Auckland, GNS Science Consultancy Report 2010/296 prepared for NZ Transport Agency, November 2011.

MfE (2002). Ambient air quality guidelines, 2002 Update, Air Quality Report No 32 prepared by the

Ministry for the Environment and the Ministry of Health, May 2002.

NIWA (2009). Air quality monitoring in the Terrace and Mt Victoria tunnels, Wellington, NIWA Report AKL-

2009-021 prepared for NZ Transport Agency, June 2009.

NIWA (2010a). Guidance for the management of air quality in road tunnels in New Zealand, NIWA Report

AKL-2010-045 prepared for NZ Transport Agency, December 2010.

NIWA (2010b). Stocktake of air quality in and around State Highway tunnels, NIWA Report AKL-2010-016

prepared for NZ Transport Agency, April 2010.

NIWA (2010c). A regression approach to assessing urban NO2 from passive monitoring – Application to the

Waterview Connection. NIWA Report AKL-2010-023 prepared for NZ Transport Agency, June 2010.

NZ Transport Agency (2008). Environmental Plan, version 2, Transit NZ (now NZ Transport Agency), June

2008.

NZ Transport Agency (2009). NZ Transport Agency standards for air quality in road tunnels, Memo to

Value Assurance Committee by Carl Reller, Rudolph Kotze, and Rob Hannaby, 24 September 2009.

NZ Transport Agency (2012a). Ambient air quality (nitrogen dioxide) monitoring programme – operating

manual 2012/13, prepared by Watercare Services Ltd and Emission Impossible Ltd for NZ Transport

Agency, September 2012.

NZ Transport Agency (2012b). Ambient air quality (nitrogen dioxide) monitoring network – Annual report

2007 to 2011, NZ Transport Agency, September 2012.

T Sullivan (2013) of Auckland Motorway Alliance, pers. comm., regarding the maintenance and calibration

of the in-tunnel sensors, 4 February

WHO (2006). Air Quality Guidelines Global Update 2005: Particulate matter, ozone, nitrogen dioxide, and

sulphur dioxide, World Health Organisation, October 2006.

WSL (2010a). NZ Transport Agency Johnstone’s Hill tunnels - Passive nitrogen dioxide air quality

monitoring report March to June 2010, Report prepared by Watercare Services Ltd for NZ Transport

Agency, August 2010.

WSL (2010b). NZ Transport Agency Johnstone’s Hill tunnels - Continuous air quality monitoring report 30

March to 13 July 2010, Report prepared by Watercare Services Ltd for NZ Transport Agency, August 2010.


7. Glossary

Terms Description

AADT Annual average daily traffic

AAQG MfE Ambient Air Quality Guidelines

AMA The Auckland Motorway Alliance is a formal alliance led by the Transport

Agency with Fulton Hogan, Opus, Beca, Resolve Group and Armitage Systems

Ltd. The AMA is responsible for the maintenance and operation of the Auckland

Motorway network and SH22, including renewals, and special projects but not

large capital projects or planning issues.

AQNES National Environmental Standards for Air Quality, which set standards for

ambient air quality for key air pollutants to protect health. The AQNES apply to

any location outdoors where people are likely to be exposed. The full title is

Resource Management (National Environmental Standards for Air Quality)

Regulations 2004.

CO Carbon monoxide, an air pollutant produced from incomplete combustion of

fuels, eg diesel and petrol used in transport. CO can cause health effects such

as asphyxia.

EIL Emission Impossible Limited

Exceedance An occasion when the concentration of an air pollutant exceeds a standard or

permissible measurement.

GNS Institute of Geological and Nuclear Sciences

HCV A heavy commercial vehicle is a motor vehicle (other than a motorcar that is not

used, kept, or available for the carriage of passengers for hire or reward) having

a gross laden weight exceeding 3500kg.

MfE Ministry for the Environment

NIWA National Institute of Water and Atmospheric Research

NO2 Nitrogen dioxide, an air pollutant produced from the combustion of fossil fuels

used in transport. NO2 can cause health effects such as retarded lung

development in children and increased susceptibility to lung infections.

NOX Nitrogen oxides, the collective term for air pollutants containing a mixture of

nitrogen and oxygen

Passive monitoring Air quality monitoring undertaken by collecting airborne gases through a

diffusion barrier onto a sorbent medium without the use of a vacuum source, eg

diffusion tubes.

PIARC Permanent International Association of Road Congresses

PM2.5

Fine particulate matter less than 2.5µm in diameter, an air pollutant produced

from the combustion of transport fuels, primarily diesel

PM10

Particulate matter less than 10µm in diameter, an air pollutant produced from

the combustion of transport fuels, primarily diesel. PM10

can cause serious

health effects such as increased cardio-respiratory illness and premature death.

Although PM2.5

is of increasing concern, because its emissions relate more

directly to observed health effects, PM10

is commonly used in air quality

assessments as it covered by an AQNES and more comprehensive monitoring


records exist.

ppm Parts per million, a measure of concentration

SH State highway, eg SH1N is State Highway 1 North

Source apportionment All air pollution has a unique combination of chemical elements depending on

the source. Source apportionment establishes these ‘fingerprints’ or ‘signatures’

and uses them to quantify the contributing sources to air particulates (PM2.5

or

PM10

).

µg Microgram, a millionth of a gram

µm Micrometre, a millionth of a metre

WHO World Health Organisation

WSL Watercare Services Limited

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